1. Field of the Invention
The present invention relates to a broadband wireless access system. More particularly, the present invention relates to an apparatus and a method for signaling of a connect/disconnect message during group communication in a broadband wireless access system.
2. Description of the Related Art
As a communication system develops, a broadband wireless access system can provide various kinds of services with a high transmission rate. Accordingly, research for providing various additional services as well as one-to-one telephone communication, which is the general communication of the related art, via the broadband wireless access system is in progress. For example, a group communication, specifically, a Push To Talk (PTT) service via the broadband wireless access communication system is considered. As one of standardization activities for the PTT service, the Open Mobile Alliance (OMA), which is an organization establishing an open type standard used in a mobile communication terminal, proposes an OMA PTT over Cellular (PoC) standard for the PTT service.
According to the OMA PoC standard, after a session is pre-established, a PTT terminal transmits a REFER message to a control PoC server in order to communicate. Accordingly, a participating PoC server receives an INVITE message from the control PoC server, transmits a Media Burst Control Protocol (MBCP) connect message to a counterpart PTT terminal in a unicast method, and receives a MBCP Media Burst Acknowledgement message from the counterpart PTT terminal.
At this point, in the case where the control PoC server transmits a plurality of INVITE messages using the same RFFER message, since the MBCP Connect message is doubly transmitted in a unicast method by the number of the INVITE messages, an excessive signaling overhead occurs. Similarly, an MBCP disconnect message is also doubly transmitted in a unicast method by the number of BYE messages.
In addition, when the counterpart PTT terminal operates in an idle mode in a wireless access network, the counterpart PTT terminal that has received the MBCP connect message has to make a transition to an awake mode in order to transmit the MBCP Media Burst Acknowledgement message. Accordingly, when a plurality of terminals serving as objects of group communication are in an idle mode, paging signaling for allowing the plurality of terminals to make a transition to the awake mode from the idle mode and signaling for exiting the idle mode occur excessively, and as a result, a system overload and a communication delay occur. Furthermore, since the number of terminals operable in an awake mode in a wireless access network is limited, the number of terminals that can simultaneously perform group communication is limited by the number of the terminals operable in the awake mode.
Therefore, in performing group communication using a broadband wireless access system, there is a need for an apparatus and a method for preventing occurrence of an excessive signaling overhead by an awake mode entry.